Moved tree topology into separate class `byte_tree`.
Removed node_count variable.
Simplified pc_node struct.
Moved t_dfs_shape parameter into tree strategy class.
Removed unnecessary c_str() calls and replaced on

std::remove call by sdsl::remove.
Fixed template parameters.
Replaced magic numbers by constant.
Now POD-vectors can also be serialized and loaded.
First working version of integer versions of HuTucker

and Huffman-shaped wavelet trees.
Fixed serialized method.
static const integer consts -> enum
Removed use of `undef`-node in wt_pc.
Removed use of `undef`-node in wt_pc.
Fixed structure tree node merge.
serialize_vector can now serialize vectors of type std::string
Merge pull request #32 from mpetri/std-vector-serialize

serialize_vector can now serialize vectors of type std::string
simplified structure tree
fixed bug in the way new children are 'hashed'
Merge pull request #33 from mpetri/structure-tree-simplified

simplified structure tree to automatically combine identical children
Experiment with the nullstream.